A Not held order is an order that gives the floor broker or trader on a NASDAQ desk discretion as to the time and price of execution.
Applying "Not Held Order (NH)" to Securities Exams:
A investor usually a large or sophisticated investor who wants to purchase or sell a block of stock may at time give the floor broker the authority to determine the time and price at which the order is executed. A not held order as the name indicates states that the floor broker will not be held responsible if the order could have been filled at a better price later in the trading session. You will likely see a number of questions dealing with how and when orders are placed on your exam. It is important to make sure you know each type of order qualifier such as a not held order, all or none, as well as limit and stop orders such as buy limits and sells stops.